Spectros Corporation is developing a guidance system that assists with the localization of sentinel lymph nodes in breast cancer. Under Phase I support, a probe will be developed for accurate node localization without need for the radioactive technetium tracer currently used. The Spectros system spectroscopically analyzes tissue surrounding a probe. By indicating when the probe is pointed toward tissue containing Isosulfan Blue at a depth of up to 5 cm, the likelihood of obtaining a diagnostic biopsy is increased. The core technology has been validated in animals to guide needles to target sites, and in humans to detect cerebral hemorrhage through the intact skull. In Phase I, an existing Spectros probe will be modified for use during node localization. Model systems, similar in optical absorbance and scattering to human tissue, will be constructed to calibrate and test the probe. Under IRB approval, in vivo axillary node data will be collected from patients scheduled to have biopsy performed using Isosulfan Blue. Localization of the node(s) by the probe will be cross-validated with actual location as determined surgically. The result of this project will be an optical probe for localization of Isosulfan-positive lymph nodes, with pilot data in human subjects. PROPOSED COMMERCIAL APPLICATIONS: Spectros will develop a commercial guidance system for sentinel node biopsy. Breast cancer is a leading cause of death in women. Accurate node biopsy is key to treatment selection and patient survival. 100-200K patients/year are sentinel node biopsy candidates. The market for an improved lymph biopsy system is estimated at $20-40MM/year (1995 breast ca. market was $916MM). Extensions to focal therapeutics and targeted drug delivery are envisioned.